Screed



March 14, 1939. s. R, BLACKWELL SCREED Filed Aug. 5, 1936 5 Sheets-Sheet1 S R. BLACKWELL SCREED Filed Aug. 5, 1956 3 Sheets-Sheet 2 NMW mw, Nn

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S. R. BLACKWELL SCREED Filed Aug. 5, 1936 3 Sheets-Sheet 3 VEN rolaBLAU/f WEL L ATTORNEY Patented Mar. 14, 1939 UNITED STATES PATENT oFFlcEApplication August 5,

'l Claims.

This invention relates to a new and useful improvement in screeds, andhas for its object to provide a vertically adjustable' screed ofrelatively simple but durable and eillcient construction.

In concrete road construction a typical road is twenty feet wide, and ona straight stretch of road a one-inch crown in the center of said roadis usually provided. This crown tapers from its m maximum at the centerto nothing at the sides abutting the shoulders. On a curve there isusually only a tangent running from the outside of the curve to theinside of said curve. It is extremely important in road constructionwork to conserve labor expense, and in my device the labor of regulatingthe elevation of or adjusting the pitch of the bottom shoe ofv thescreed is reduced to a minimum of time, being such only as is requiredin turning a handwheel, which in turn rotates a sha'ft'which controls aseries of eccentrics which determine at points across the screed theheight of the bottom shoe of said screed from the straight base lineacross the roadway from one side fornito the other.

In the only adjustable screeds of which I am aware it takes more thanone hour to adjust the bottom shoe of the screed, and as this isexpensive labor involved in this work and in the loss of time of otherallied employees, it is highly important that the time required for suchadjustment should be reduced to a minimum.

Fig. 1 is a front elevation of my improved screed and a part of thesupporting structure thereof, with the two side forms of the road insection.

Fig. 2 is a rear elevation of my improved screed with the two side formsof the road in section.

Fig. 3 is an end view of my improved screed with one road side formpartly broken away and parts of the screed-supporting structure partlybroken away.

Fig. 4 is a. view taken on the line -Ji, Fig. 1, looking in thedirection of the arrows.

Fig. 5 is a view taken on the line 5 5, Fig. 1, looking in the directionof the arrows.

45 Fig. 6 is a view taken on the line 6 6, Fig. 2,

looking in the direction of the arrows.

Fig. '7 is a side elevation of the dial and pointer shown in Fig. 8.

Fig. 8 is a front elevation of the dial and pointer, with the shaft onwhich said pointer is mounted being in section.

Fig. 9 is a diagrammatical view of the settings of the eccentrics forforming a one-inch center crown diminishing to nothing at the sides ofthe road of a twenty foot roadway.

193s, serial Nt. 94,335 (Cl. 94-45) Fig. l0 is also a diagrammaticalview of the settings of the eccentrics for forming a one-inch crown atthe center twenty foot section of a forty foot road, where the crownmerges into a tangent which proceeds from the side ten feet 5 on eachside of the road.

In the drawings, A generally designates a supporting structure for thescreed B, said supporting structure being motor driven and mounted onflanged traction wheels C which ride on the road 10 side forms D. Thescreed B asa. whole may be raised or lowered by the mechanism E attachedto the chains F at the sides of the screed. The mechanism E is under thecontrol of the operator of the structure.

A transverse reciprocatory movement is imparted to the screed B as itadvances over the work by the crank G attached bythe rod I-I to the beamof the screed B. The crank G is operated by a gasoline motor (not shown)on the sup- 20 porting structure A. Such reciprocatory movement is inthe arc of a circle so that the circular crown of the road is notdisturbed by such movement, which is usually only a few inches.

The screed B has a beam i at its upper portion 25 which is formed from ash'eet of metal and is provided with a short, downwardly depending,stiening flange 2 at its rear edge and a longer, downwardly dependingange or apron 3 at its forward edge. To the flange or apron 3 is se- 30cured a protector plate 4 by a series of bolts 5 and t at the upper andlower portions, respectively, of the ange 3. The purpose of thisprotector plate is to prevent the entrance of the cement and alliedmaterials into the working parts 35 controlling the screed B.

To the lower portion of the flange 3 is secured a relatively flexiblebottom shoe l which has a substantially flat bottom face f3. The innerend of the bottom shoe l is upturned as at 9 to form 40 a stieningmember. Adjacent the upturned end 9 is a stidening bar ill extendingacross the bottomy shoe l from side to side.

The bar l0 is held in place by clamps il secured by the bolts l2 passingthrough the rear 45 end of the bottom shoe l. The stiifening member 9and bar lil are placed at the rear end of the bottom shoe l to equalizethe movement of both the front and rear portions of said shoe whenpressure to vertically position said shoe is a'p-` 50v plied. The lengthof these stiifening members being twenty feet and they being relativelythin in cross section, they do not retard the vertical adjustment ofsaid shoe by the eccentrics 29.

At spaced intervals across the upper portion of 55 the bottom shoe 1brackets are attached to said bottom shoe. preferably by rivets Il (seeFigs. 5 and 6). These brackets I3 are also secured to the flange 3 bythe bolts 6 which pass through slots I5 in the forward portion of thesaid brackets I3 (see Fig. 5), to permit of vertical movement of saidbrackets with respect to said flange. At each end of the screed B arehangers I3 extending from the beam I tothe bottom shoe 1.

The upwardly extending portion I1 of the bottom shoe 1 is provided witha series of notches I8 extending downwardly from the top of the portionI1 to where the bottom shoe 'I projects rearwardly from the portion I1.The purpose of these notches is to render the bottom shoe 1 fiexible sothat it may be readily adjustable by the means hereinafter to bedescribed.

At each side of the screed B are end shoe baille plates I9. The bottomshoe 1 is also supported by a series of hangers 20 (see Figs. 2 and 4).The upwardly extending portion I1 is slotted as at 2I to receive thebolt 6. By virtue of said slots the bottom shoe 1 is permitted verticalmovement with respect to the flange 3.

A shaft 22 extends from one side of the screed B to the other and ismounted in each of the brackets I3 in a bearing fit. The shaft 22 isrotatable a one-half revolution by the worm wheel 23, keyed to saidshaft as at 24, said worm wheel being operable by the worm 25 mounted onthe shaft 26 passing through the supporting and bearing plate 21 rivetedto the beam I of the screed B. The shaft 26 is manipulated by thehandwheel 28 located adjacent the operator of the device. The worm wheel23 and the worm 25 are encased in the housing J.

On the shaft 22 are a series of eccentrics 23 held to said shaft by thekeys 33. In Fig. 2 the brackets I3 on the bottom shoe 1 are usuallyspaced about 2 ft. apart. 'I'he shaft 22 has a bearing t in each of thebrackets I3 so as to cause said brackets to raise or lower as the shaft22 is turned. Where the shaft rotates only fractionally at periodicaltimes, the curvature thrownf into the shaft by the operation of the cam29 in the ring 3|' carried by the lower end of the rod 3| is notobjectionable, as it throws no particular strain on said shaft, as itwould if said shaft were constantly rotated. 'I'he shaft is onlydeflected from a straight line commencing near the outer sides of thescreed to a maximum not exceeding 2 inches, the standard crown beingapproximately l inch, so that the shaft 22 is never deflectedsubstantially, and as only a slight amount of rotation is imparted tosaid shaft in order to provide for a diierent curvature of the surfaceof the concrete road, such slight deviation from a straight line has noeffect whatever on the life of the shaft. The bottom shoe 1 may not haveto be adjusted for a period of several days if the grade or angle of theroad surface remains the same.

The rods 3| are adjustable with respect to the beam I by the nuts 32,for the reason that should the beam-be dented or bent lor sag, the rods3| can be adjusted through the nuts 32 to equalize the distance betweenthe shaft 22 and thebeam I by virtue of adjusting the rods 3|. It willbe noted that the ends of the nuts 32 on the rods 3| which contact theupper and lower faces of the beam I are beveled to permit of the slightswinging movement of the rods 3| as the eccentric in the ring carried bythe lower end of the rod 3l is turned. The eccentrics or cams 29co-operate with the shaft 22 to raise or lower the brackets I3 and thusdeflect the bottom shoe 1. These eccentrics are supported on the beam Iby the rods 3| through the rings 3|' and are primarily adjusted by thenuts 32 above and below the beam I. The nuts 32 are beveled at theircontact with the beam I to permit the rods 3| to swing as the shaft 22is rotated by the worm 25. A'dial 33 is mounted on the screed B at apoint where it may be seen by the operator of the device. A pointer 34is fixed on the shaft 22 by the set screw '35 and indicates on the dial;33 the position of the bottom shoe 1 when adjusted by'the eccentrics 29.

A further support K for the screed B is shown in Fig. 4. As this supportconstitutes no part of my invention, it is believed the illustration inFig. 4 is sufficiently descriptive of said support.

In the diagrammatical drawing shown in Fig. 9 provision is shown forputting a one-inch crown in a twenty foot wide road. Starting at zero atthe sides L, the surface of the road gradually rises on the arc of acircle to a one-inch crown in the center of the road. When approaching acurve the crown is gradually eliminated and a tangent substituted. Bymanipulating the handwheel 28 and watching the dial 33, the operatorimmediately adjusts the eccentrics 29 to cause the bottom shoe 1 tomerge from the arc of a circle to a tangent of the degree specified bythe highway department for the road being constructed.

After leaving the curve the screed must again be adjusted to insert thecircular crown in thesurface of 'the road, and such adjustment is againmade the operator by manipulating the handwheei In the. diagrammaticaldrawingof Fig. 10 I have shown a twenty foot section of a forty footwide road, in which the circular crown portion is shown in theright-hand side of said drawing and the tangent portion is shown in theleft-hand side of said drawing. The tangent portion merges into thecircular crown portion at the part marked X on said drawings. It will beunderstood that when the tangent and circularscrown portions l' are setforth in the highway departments plans the eccentrics 29 of the screed Bare arranged and set accordingly, so that when the shaft 22 is rotatedthe eccentrics 29, acting through said shaft 22 and brackets I3 attachedto the flexible bottom shoe 1, adjust said shoe the required distance upor down to take care of the circular crown portion and the tangentportion as called for by said plans. As said before, such adjustment isquickly and easily made without the loss of any time and the roadworkprogresses uninterruptedly. The eccentrics are set in accordance withthe plans specified by the highway department, and the eccentrics arechanged to conform to the set up of the road being constructed.

I claim:

l. A screed comprising a beam, a flexible bottom shoe suspended fromsaid beam, a plurality.

of upwardly extending brackets rigidly fixed at' 4 flexed when saidoperating member is turned.

'2. A screed comprising a beam, a :flexible bottom shoe suspended fromsaid beam, a plurality of upwardly extending brackets rigidly xed atspaced points along the length of said ilexible bottom shoe, a pluralityof rods secured to said beam and extending downwardly therefrom, saidbrackets being suspended from said beam through said rods, a single,continuous operating member extending substantially the length of saidbottom shoe and' rotatably connected with said brackets and said rods,and eccentric means co-operating with said continuous operating memberwhereby adjacent portions of said flexible bottom shoe may be displaced,not all to the same extent, when said operating member is turned.

3. A screed comprising a beam, a flexible bottom shoe suspended fromsaid beam, a plurality of `upwardly extending brackets rigidly fixed atspaced points along the length of said flexible bottom shoe, a pluralityof rods secured to said beam and extending downwardly therefrom, saidbrackets being suspended from said beam through said rods, a single,continuous operating member extending substantially the length of saidbottom shoe and rotatably connected with said brackets and said rods,and eccentric means co-operating with said continuous operating memberwhereby said brackets are simultaneously operated to displace thecorresponding portions of said flexible bottom shoe at the points towhich said brackets are xed.

4. A screed comprising a beam, a flexible bottom shoe suspended fromsaid beam, a plurality of upwardly extending brackets rigidly ilxed atspaced points along the length of said exible bottom shoe, a' pluralityof rods secured to said beam and extending downwardly therefrom, saidbrackets being suspended from said beam through said rods, a single,continuous operating member extending substantially the length of saidbottom shoe and rotatably connected with said brackets and said rods,and eccentric means co-operating with said continuous operating member,said means being of such character as to ex the flexible bottom shoe toa diierent 'extent along the length of said bottom shoe, and means forturning said continuous operating member for operating said brackets.

5. A screed comprising a beam, a exible bottom shoe supported from saidbeam. means for flexing said flexible bottom shoe to a desiredcurvature, said means comprising a plurality of upwardly extendingbrackets provided with transverse bearing fit openings rigidly xed atspaced points along the length of said exible bottom shoe, a pluralityof apertured rods suspended from said beam downwardly to a point belowthe top of said brackets so that the apertures in said rods and thetransverse openings in said brackets are in substantial alinement, asingle, continuous, rotatable operating member passing through theopenings in said brackets and the apertures in said rods, and eccentricmeans co-operating with said operating member whereby said flexiblebottom shoe may be adjusted when said operating member is turned.

6. A screed comprising a beam, a iiexible bottom shoe supported fromsaid beam, means for flexing said flexible bottom shoe to a desiredcurvature, said means comprising a plurality of upwardly extendingbrackets provided with transverse bearings fit openings rigidly iixed atspaced points along the length of said flexible bottom shoe, a pluralityof apertured rods suspended from said beam downwardly to a point belowthe top of said brackets so that the apertures in said rods and thetransverse openings in said brackets are in substantial alinement, asingle, continuous, rotatable operating member passing through' theopenings in said brackets and the apertures in said rods, eccentricmeans co-operating with said voperating member whereby said ilexiblebottom Vshoe may be adjusted when said operating member is turned, andmeans for separately adjusting each of said rods with respect to saidbeam.

'7. A screed comprising a beam, a flexible botu tom shoe suspended fromsaid beam, means for flexing said flexible bottom shoe to a desiredcurvature, said means comprising a plurality of upwardly extendingbrackets rigidly fixed at spaced points along the length of saidflexible bottom shoe, a plurality of rods suspended from said beam andextending downwardly therefrom to a point adjacent the top of saidbrackets, asingle, continuous operating member rotatably associated withsaid brackets and saidrods, eccentric means co-operating with saidoperating member and said rods for simultaneously operating saidbrackets to displace the corresponding portions of said ilexible bottomshoe, said rods being movably mounted transversely in the beam, and nutsmounted on the ends of said rods passing through the beam and contactingthe upper and lower faces of said beam for separately adjusting each ofsaid rods.

STEPHEN/R. BLACKWELL.

